1. Field of the Invention
The invention relates generally to reciprocating pumps. In particular aspects, the invention relates to systems and methods for detecting and monitoring abnormal conditions within a pump, including cavitation.
2. Description of the Related Art
Reciprocating positive displacement pumps used in the well service industry and drilling mud pump industry are exposed to high pressure, high flow rate and abrasive fluids (slurry) for the purpose of fracturing, drilling and so forth. Reciprocating pumps can be single or double acting pumps with pistons that are driven by a crankshaft that is actuated by a motor. Reciprocating positive displacement pumps have at least one piston cylinder, but often have multiple cylinders, such as three-cylinder (triplex) and five-cylinder (quintuplex) configurations.
Cavitation affects reciprocating pumps during operation. Cavitation occurs when actual pressure reaches the vapor pressure of the fluid being pumped, and the fluid starts to vaporize. Small vapor bubbles are formed and, under compression, will implode. If these implosions occur in close proximity to the pump housings or valve surfaces, they will start to impinge the material, causing material to be removed and damaged. Cavitation can cause permanent damage and, if not prevented in time, can lead to complete destruction of the pump housing and/or associated components.
Efforts have been made to identify cavitation in an operating pump using acoustic signal analysis. However, this has proven problematic. There is a wide variety of vibration or acoustic signal responses that relate to a variety of abnormal conditions, which makes it difficult to differentiate between cavitation, valve wear, seal failure, or other conditions.